They are caused when the blood supply to the heart suddenly becomes blocked.
Without enough blood, the heart can be seriously damaged and even fatal.
If you often snore in your sleep, then you are at risk of having a heart attack, as it turned out.
Snoring could be a sign of sleep apnea, which is a risk factor for heart disease, warned the American Heart Association.
Sleep apnea is caused by pausing breathing while sleeping because the weight on the upper chest and neck blocks the airways.
If you snore unusually loudly, you are at risk of sleep apnea.
“Simple snoring can get a little annoying, especially for someone who hears it,” said the charity.
“But if a snorer repeatedly stops breathing for brief moments, this can lead to cardiovascular problems and be potentially life-threatening.
“It’s a condition known as sleep apnea, in which the person may experience pauses in breathing five to 30 times an hour or more while they sleep.
“It prevents restful sleep and has been linked to high blood pressure, cardiac arrhythmias, strokes and heart failure.
“The evidence of the link between sleep apnea and high blood pressure and cardiovascular disease in general is very strong, so people really need to know.”
If left untreated, sleep apnea can also increase your risk of having a stroke, developing an irregular heartbeat, or even developing type 2 diabetes.
You can reduce your risk of disease by losing weight if you are overweight or obese, or by reducing the amount of alcohol in your diet.
Sleeping pills or tranquilizers could make your sleep apnea worse, so it’s best to avoid them, the NHS added.
Heart attacks are a symptom of coronary artery disease – a leading cause of death in the UK and worldwide.
Symptoms of heart disease include severe chest pain – known as angina – and heart failure.
It is caused by fatty deposits in the arteries around the heart that block blood flow through the body.
Most at risk for heart disease are smokers, people with high cholesterol, and people with high blood pressure.
Coronary artery disease kills more than 150,000 people in the UK each year.